<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>关注点赞收藏三连</title>
    <style>
        body {
            margin: 0;
            padding:0;
            border: none;
        }
        #forPuzzle {
            border:none;
            left:0px;
            top:0px;
        }
        #divmenu {
            position:absolute;
            top:5px;
            left:15px;
            width:0px;
            height:0px;
            cursor:default;
            z-index:50001;
            border-radius:5px;
        }
        #divmenu.open {
            width:120px;
            height:100px;
            background-color:rgba(255,255,180,0.7);
            z-index:50001;
        }

        #divmenu .title {
            font-family: Verdana, "Bitstream Vera Sans", "Lucida Sans", sans-serif;
            font-weight:bold;
            font-size:15px;
            position:absolute;
            top:0px;
            left:30px;
            color:blue;
            background-color:rgba(255,255,180,0.7);
            padding:5px;
            border-radius:5px;
        }

        #divmenu .line {
            font-family: Verdana, "Bitstream Vera Sans", "Lucida Sans", sans-serif;
            font-weight:bold;
            font-size:15px;
            text-align:center;
            position:absolute;
            width:100px;
            left:5px;
            color:blue;
            padding:5px;
            display:none;
            border-radius:5px;
        }

        #divmenu.open .line {
            display:block;
        }
        #divmenu.open .line:hover {
            background-color: rgba(255,230,90,1);
            cursor:pointer;
        }
    </style>
</head>
<body>
<div id="forPuzzle"></div>

<script>
    "use strict";

    let autoStart;
    const mrandom = Math.random,
        mfloor = Math.floor,
        mhypot = Math.hypot;
    //-----------------------------------------------------------------------------
    function isMiniature() {
        return location.pathname.includes('/fullcpgrid/');
    }
    // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

    function alea (min, max) {
// random number [min..max[ . If no max is provided, [0..min[

        if (typeof max == 'undefined') return min * mrandom();
        return min + (max - min) * mrandom();
    }

    // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

    function intAlea (min, max) {
// random integer number [min..max[ . If no max is provided, [0..min[

        if (typeof max == 'undefined') {
            max = min; min = 0;
        }
        return mfloor(min + (max - min) * mrandom());
    } // intAlea

    //-----------------------------------------------------------------------------
    function arrayShuffle (array) {
        /* randomly changes the order of items in an array
           only the order is modified, not the elements
        */
        let k1, temp;
        for (let k = array.length - 1; k >= 1; --k) {
            k1 = Math.floor((k + 1) * Math.random());
            temp = array[k];
            array[k] = array[k1];
            array[k1] = temp;
        } // for k
        return array
    } // arrayShuffle

    //-----------------------------------------------------------------------------
    // Menu class
    /*
    Vertical single level menu

    It is called with an object containing the following properties:

      parentDiv : name of a div, or the div itself
      idDivMenu : id which will be attributed to the menu div (child of parentDiv)
      title : text for title of menu. remains visible when menu closed
      lineOffset : vertical position of 1st line of menu
      lineStep : vertical distance between top of two menu lines
      lines : Array. Each element of this array is an object with two properties :
              - text : text line
              - func : "onclick" callback associated with line

    */

    function Menu(params) {

        let parentDiv = params.parentDiv;
        if (typeof(parentDiv) == 'string') parentDiv = document.getElementById(parentDiv);
// div menu
        let divMenu=document.createElement('div');
        divMenu.setAttribute ("id",params.idDivMenu);
// title
        let dt = document.createElement('div');
        dt.classList.add('title');
        dt.appendChild(document.createTextNode(params.title));
        let that = this;
        dt.addEventListener("click",()=>that.display());
        divMenu.appendChild(dt);
        this.list = [];
        for (let k = 0; k < params.lines.length; ++k){
            dt=document.createElement('div');
            dt.classList.add('line');
            dt.appendChild(document.createTextNode(params.lines[k].text));
            dt.style.top=(params.lineOffset + k * params.lineStep) + "px";
            dt.addEventListener("click",params.lines[k].func);
            divMenu.appendChild(dt);
            this.list.push(dt);
        }
        divMenu.style.height = (params.lineOffset + params.lines.length * params.lineStep) +'px'
        this.divMenu = divMenu;
        parentDiv.appendChild(divMenu);

    } // Menu

    Menu.prototype.collapse = function() {
        this.divMenu.classList.remove('open');

    }
    Menu.prototype.display = function() {
        this.divMenu.classList.add('open');

    }

    //-------------------------------------------------------------------------

    // Point - - - - - - - - - - - - - - - - - - - -
    function Point(x,y) {
        this.x = Number(x);
        this.y = Number(y);
    } // Point

    Point.prototype.copy = function() {
        return new Point(this.x,this.y);
    }
    // end Point - - - - - - - - - - - - - - - - - - - -

    // Segment - - - - - - - - - - - - - - - - - - - -
    // those segments are oriented

    function Segment(p1,p2) {
        this.p1=new Point(p1.x,p1.y);
        this.p2=new Point(p2.x,p2.y);
    }

    Segment.prototype.length = function() {
        var dx = this.p1.x - this.p2.x;
        var dy = this.p1.y - this.p2.y;
        return mhypot(dx, dy);
    }
    Segment.prototype.dx =function() {
        return this.p2.x-this.p1.x;
    }
    Segment.prototype.dy =function() {
        return this.p2.y-this.p1.y;
    }


    // returns a point at a given distance of p1, positive direction beeing towards p2

    Segment.prototype.pointOnRelative = function (coeff) {
// attention if segment length can be 0
        var dx= this.p2.x-this.p1.x;
        var dy= this.p2.y-this.p1.y;
        return new Point(this.p1.x+coeff*dx, this.p1.y+coeff*dy);
    }

    // end Segment
    //-------------------------------------------------------------------------
    let uploadFile;
    { // scope for uploadFile

        let options, callBack;

        let elFile = document.createElement('input');
        elFile.setAttribute('type', 'file');
        elFile.style.display = 'none';
        elFile.addEventListener("change", getFile);

        function getFile() {

            if (this.files.length == 0) {
                returnLoadFile ({fail: 'no file'});
                return;
            }
            let file = this.files[0];
            let reader = new FileReader();

            reader.addEventListener('load', () => {
                if (options.image) options.image.src = reader.result;
                returnLoadFile ({success: reader.result, file: file});
            });
            reader.addEventListener('abort', () => {
                returnLoadFile ({fail: 'abort'});
            });
            reader.addEventListener('error', () => {
                returnLoadFile ({fail: 'error'});
            });

            if (options.image || options.readMethod == 'readAsDataURL')
                reader.readAsDataURL(this.files[0]);
            else
                reader.readAsText(this.files[0]);

        } // getFile

        function returnLoadFile(returnedValue) {
            callBack(returnedValue);
        }

        uploadFile = function(ocallBack, ooptions) {
            /* loads a file asynchronously
            at the end of the process, calls the function 'callBack' with an object :

            {fail: string} in case of failure, where string gives the reason of the failure
            or
            {success : string, file: file} where string is the content of the image file
               file represents the loaded file, and may be tested for file.type, file.name...

            CAUTION ! If the user clicks 'cancel' when loading a file, nothing happens.

            options is an object, with 0, one or more of the following properties :
            accept : string to pass as "accept" attribute to the load file button, such as '.txt' or 'image/*'
                        default : no value (will accept  * . * )
            readMethod : 'readAsText' or 'readAsDataURL' - default is readAsText
            image: if provided, must be an Image element. If possible, the data is loaded
            with readAsDataURL, no matter the value of readMethod, and option.image.src is set to the data.
            The function then returns normally as defined above.
            Normally, a 'load' event should be triggered on the image.
            */

            options = ooptions;
            callBack = ocallBack;
            if (options.accept) elFile.setAttribute("accept", options.accept);
            else elFile.removeAttribute("accept");
            elFile.click();

        } // uploadFile
    } //  // scope for uploadFile

    // -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -   -
    // side of a piece

    function Side() {
        this.type = ""; // "d" pour straight line or "z" pour classic
        this.points = []; // real points or Bezier curve points
    } // Side

    // -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -   -

    /* modifies this Side
      changes it from a straight line (type "d") to a complex one (type "z")
      The change is done towards the opposite side, between corners ca and cb
    */

    Side.prototype.twist = function(ca, cb, tgx, tgy) {

        const seg0 = new Segment(this.points[0], this.points[1]);
        const dxh = seg0.dx();
        const dyh = seg0.dy();

        const seg1 = new Segment(ca, cb);
        const mid0 = seg0.pointOnRelative(0.5);
        const mid1 = seg1.pointOnRelative(0.5);

        const segMid = new Segment(mid0, mid1);
        const dxv = segMid.dx();
        const dyv = segMid.dy();

        const pa = pointAt(5 / 12, 1 / 12);
        const pb = pointAt(4 / 12, 3 / 12);
        const pc = pointAt(1 / 2, 4 / 12);
        const pd = pointAt(1 - 4 / 12, 3 / 12);
        const pe = pointAt(1 - 5 / 12, 1 / 12);

        this.points = [seg0.p1,
            new Point(seg0.p1.x + 5 / 12 * dxh * 0.52,
                seg0.p1.y + 5 / 12 * dyh * 0.52),
            new Point (pa.x - 1 / 12 * dxv * 0.72,
                pa.y - 1 / 12 * dyv * 0.72),
            pa,
            new Point (pa.x + 1 / 12 * dxv * 0.72,
                pa.y + 1 / 12 * dyv * 0.72),

            new Point (pb.x - 1 / 12 * dxv * 0.72,
                pb.y - 1 / 12 * dyv * 0.72),
            pb,
            new Point (pb.x + 1 / 12 * dxv * 0.52,
                pb.y + 1 / 12 * dyv * 0.52),
            new Point (pc.x - 2 / 12 * dxh * 0.52 * tgx,
                pc.y - 2 / 12 * dyh * 0.52 * tgy),
            pc,
            new Point (pc.x + 2 / 12 * dxh * 0.52 * tgx,
                pc.y + 2 / 12 * dyh * 0.52 * tgy),
            new Point (pd.x + 1 / 12 * dxv * 0.52,
                pd.y + 1 / 12 * dyv * 0.52),
            pd,
            new Point (pd.x - 1 / 12 * dxv * 0.72,
                pd.y - 1 / 12 * dyv * 0.72),
            new Point (pe.x + 1 / 12 * dxv * 0.72,
                pe.y + 1 / 12 * dyv * 0.72),
            pe,
            new Point (pe.x - 1 / 12 * dxv * 0.72,
                pe.y - 1 / 12 * dyv * 0.72),
            new Point(seg0.p2.x - 5 / 12 * dxh * 0.52,
                seg0.p2.y - 5 / 12 * dyh * 0.52),
            seg0.p2];
        this.type = "z";

        function pointAt (coeffh, coeffv) {
            return new Point (seg0.p1.x + coeffh * dxh + coeffv * dxv,
                seg0.p1.y + coeffh * dyh + coeffv * dyv)
        }

    } //
    // -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -   -

    /*
    draws the path corresponding to a side
    Parameters :
      ctx : canvas context
      shiftx, shifty : position shift used to create shadow effect
      backwards : boolean, must be true for bottom and left sides, which must be drawn
          from the last point to the first
      withoutMoveTo : to decide whether to do a moveTo to the first point. Without MoveTo
      must be done only for the first side of a piece, not for the following ones
    */

    Side.prototype.drawPath = function(ctx, shiftx, shifty, backwards, withoutMoveTo) {

        let k, mix, miy;

        if (backwards) {
            if (!withoutMoveTo) {
                ctx.moveTo(this.points[this.points.length - 1].x - shiftx, this.points[this.points.length - 1].y - shifty);
            }
            if(this.type == "d") {
                ctx.lineTo(this.points[0].x - shiftx, this.points[0].y - shifty);
            } else { // jigsaw side
                for (k = this.points.length - 2 ; k > 0; k -= 3) {
                    ctx.bezierCurveTo(this.points[k].x - shiftx, this.points[k].y - shifty,
                        this.points[k - 1].x - shiftx, this.points[k - 1].y - shifty,
                        this.points[k - 2].x - shiftx, this.points[k - 2].y - shifty);
                } // for k
            } // if jigsaw side
        } else {
            if (!withoutMoveTo) {
                ctx.moveTo(this.points[0].x - shiftx, this.points[0].y - shifty);
            }
            if(this.type == "d") {
                ctx.lineTo(this.points[1].x - shiftx, this.points[1].y - shifty);
            } else { // edge zigzag
                for (k = 1 ; k < this.points.length - 1; k += 3) {
                    ctx.bezierCurveTo(this.points[k].x - shiftx, this.points[k].y - shifty,
                        this.points[k + 1].x - shiftx, this.points[k + 1].y - shifty,
                        this.points[k + 2].x - shiftx, this.points[k + 2].y - shifty);
                } // for k
            } // if jigsaw side
        }
    } // Side.prototype.drawPath

    // end Side
    // -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -   -

    function Piece(kx, ky) { // object with 4 sides
        this.ts = new Side(); // top side
        this.rs = new Side(); // right side
        this.bs = new Side(); // bottom side
        this.ls = new Side(); // left side
        this.kx = kx;
        this.ky = ky;
    }

    // -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -   -
    /* draw path for one piece
      shiftx and shifty used for shadow effect
      does from beginPath to closePath, but not actually draw : no stroke nor fill nor clip here
    */

    Piece.prototype.drawPath = function (ctx, shiftx, shifty, withoutBeginPath) {

        if (withoutBeginPath !== true) ctx.beginPath();

        this.ts.drawPath(ctx, shiftx, shifty, false, false); // top side
        this.rs.drawPath(ctx, shiftx, shifty, false, true);  // right side
        this.bs.drawPath(ctx, shiftx, shifty, true, true);   // bottom side
        this.ls.drawPath(ctx, shiftx, shifty, true, true);   // left

    } //

    // -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -   -
    /*
    creates and returns a div for an individual piece, with a canvas with shadow, and a part of the picture
    canvas and div are three times the average size of pieces
    puzzle object given in parameters provides required elements
    scale and x and y offsets allow to scale and truncate picture to actual size
    */

    Piece.prototype.createDivPiece = function(puzzle, scale, offsx, offsy) {

        let ctx, shiftx, shifty;
        this.theDiv = document.createElement('div');
        this.theDiv.style.width = 3 * puzzle.dx + "px";
        this.theDiv.style.height = 3 * puzzle.dy + "px";
        this.theDiv.style.position = "absolute";

        this.theCanv = document.createElement('canvas');
        this.theCanv.width = 3 * puzzle.dx;
        this.theCanv.height = 3 * puzzle.dy;

// origine shifting for path drawing
        shiftx = puzzle.dx * (this.kx - 1);
        shifty = puzzle.dy * (this.ky - 1);

        ctx = this.ctx = this.theCanv.getContext("2d");
        this.drawPath(ctx, shiftx, shifty);

        ctx.clip();


        let sx, sy, sWidth, sHeight, dx, dy,dWidth, dHeight;
        if (this.kx == 0) {
            sx = 0 * puzzle.dx / scale + offsx; // won't work on safari if offsx < 0
            dWidth = 2 * puzzle.dx;
            dx = puzzle.dx;
        } else {
            sx = (this.kx - 1) * puzzle.dx / scale + offsx;
            dWidth = 3 * puzzle.dx;
            dx = 0;
        }
        sWidth = dWidth / scale;
        if (this.ky == 0) {
            sy = 0 * puzzle.dy / scale + offsy; // won't work on safari if offsy < 0
            dHeight = 2 * puzzle.dy;
            dy = puzzle.dy;
        } else {
            sy = (this.ky - 1) * puzzle.dy / scale + offsy;
            dHeight = 3 * puzzle.dy;
            dy = 0;
        }
        sHeight = dHeight / scale;

        ctx.drawImage(puzzle.image, sx, sy, sWidth, sHeight,
            dx, dy, dWidth, dHeight);
// shadow effect
// depends on size of pieces

        let shift = 1, thickness = 2;
        if (puzzle.dx > 100 && puzzle.dy > 100) {
            shift = 2; thickness = 5;
        } else if (puzzle.dx > 50 && puzzle.dy > 50) {
            shift = 1.5; thickness = 3;
        }

        this.drawPath(ctx, shiftx + shift, shifty + shift);
        ctx.lineWidth = thickness;
        ctx.strokeStyle = "rgba(0, 0, 0, 0.3)";
        ctx.stroke();
        this.drawPath(ctx, shiftx - shift, shifty - shift);
        ctx.lineWidth = thickness;
        ctx.strokeStyle = "rgba(255, 255, 255, 0.3)";
        ctx.stroke();
        this.drawPath(ctx, shiftx, shifty); // path used for selection of the piece

        /* place of the piece at the beginning of the game */
        this.moveTo(new Point((this.kx - 1) * puzzle.dx + Puzzle.MARGIN1,
            (this.ky - 1) * puzzle.dy + Puzzle.MARGIN1));

        this.theDiv.appendChild(this.theCanv);

        return this.theDiv;
    } // createDivPiece
    // -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -   -

    // returns position of current piece

    Piece.prototype.where = function() {
        let x, y;
        x = parseFloat(this.theDiv.style.left);
        y = parseFloat(this.theDiv.style.top);
        return new Point(x, y);
    } // Piece.prototype.where

    // -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -   -
    /* move piece to a given location
    onePoint if location of top lefthand corner of div (far beyond visible par of piece)
    */
    Piece.prototype.moveTo = function(onePoint) {
        this.theDiv.style.top = onePoint.y + "px";
        this.theDiv.style.left = onePoint.x + "px";
    } // Piece.prototype.moveTo

    // -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -   -
    // true if given (mouse) coordoninates are inside the piece

    Piece.prototype.insidePiece = function(x, y) {

        let styl = getComputedStyle(this.theDiv);
        let xloc = x - parseFloat(styl.left); // 'local' x and y
        let yloc = y - parseFloat(styl.top);

        return this.ctx.isPointInPath(xloc, yloc);

    } // Piece.prototype.insidePiece

    // fin Piece


    //--------------------------------------------------------------
    //--------------------------------------------------------------
    // class PolyPiece
    // represents a group of pieces well positionned with respect  to each other.
    // pckxmin, pckxmax, pckymin and pckymax record each a piece with highest kx, lowest kx...


    function PolyPiece(initialPiece, puzz) {
        this.pckxmin  =
            this.pckxmax  =
                this.pckymin  =
                    this.pckymax = initialPiece;
        this.pieces = [initialPiece];
        this.puzzle = puzz;
    } // PolyPiece

    // -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -   -
    /*
      this method
        - adds pieces of otherPoly to this PolyPiece
        - adjusts coordinates of new pieces to make them consistent with this polyPiece
        - does not re - evaluate the z - index of the polyPieces
    */

    PolyPiece.prototype.merge = function(otherPoly) {

        for (let k = 0; k < otherPoly.pieces.length; ++k) {
            this.pieces.push(otherPoly.pieces[k]);
            // watch leftmost, topmost... pieces
            if (otherPoly.pieces[k].kx < this.pckxmin.kx) this.pckxmin = otherPoly.pieces[k];
            if (otherPoly.pieces[k].kx > this.pckxmax.kx) this.pckxmax = otherPoly.pieces[k];
            if (otherPoly.pieces[k].ky < this.pckymin.ky) this.pckymin = otherPoly.pieces[k];
            if (otherPoly.pieces[k].ky > this.pckymax.ky) this.pckymax = otherPoly.pieces[k];
        } // for k

        this.moveTo(this.where()); // to set positions of new pieces

// sort the pieces by increasing kx, ky

        this.pieces.sort(function(p1, p2){
            if (p1.ky < p2.ky) return  - 1;
            if (p1.ky > p2.ky) return 1;
            if (p1.kx < p2.kx) return  - 1;
            if (p1.kx > p2.kx) return 1;
            return 0; // should not occur
        });

    } // merge

    // -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -   -
    PolyPiece.prototype.where = function() {
        return this.pieces[0].where();
    } // PolyPiece.prototype.where

    // -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -   -
    // the position of the PolyPiece is this of its 1st piece
    // the position of the others is evaluated on this basis

    PolyPiece.prototype.moveTo = function(pnt) {

        this.pieces[0].moveTo(pnt);
        for (let kp = 1; kp < this.pieces.length; ++kp) {
            this.pieces[kp].moveTo(new Point(pnt.x + this.puzzle.dx * (this.pieces[kp].kx - this.pieces[0].kx ),
                pnt.y + this.puzzle.dy * (this.pieces[kp].ky - this.pieces[0].ky )));
        } // for kp
    } // PolyPiece.prototype.moveTo

    // -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -   -
    PolyPiece.prototype.ifNear = function(otherPoly) {

        let p1, p2;
        for (let kp = 0; kp < this.pieces.length; ++kp) {
            p1 = this.pieces[kp];
            for (let kn = 0; kn < otherPoly.pieces.length; ++kn) {
                p2 = otherPoly.pieces[kn];
// p2 above p1 ?
                if ((p1.kx == p2.kx && p1.ky == p2.ky + 1) &&
                    (this.puzzle.near(p1, p2, 0, - 1))) return true;
// p2 below p1 ?
                if ((p1.kx == p2.kx && p1.ky == p2.ky - 1) &&
                    (this.puzzle.near(p1, p2, 0, 1))) return true;
// p2 left of p1 ?
                if ((p1.kx - 1 == p2.kx && p1.ky == p2.ky) &&
                    (this.puzzle.near(p1, p2, - 1, 0))) return true;
// p2 right of p1 ?
                if ((p1.kx + 1 == p2.kx && p1.ky == p2.ky) &&
                    (this.puzzle.near(p1, p2, + 1, 0))) return true;
            } // for kn
        } // for kp
        return false; // no, not near
    } // ifNear

    // end class PolyPiece
    //--------------------------------------------------------------
    //--------------------------------------------------------------
    // puzzle

    /* see createPuzzle for the 'params' parameter
    This constructor is used to load the picture, the actual construction of the
    puzzle can't be done before picture dimensions are known
    */

    function Puzzle(params) {

// image - by url (src) or straight image object
        if (typeof(params.img) == 'string') {
            this.image = new Image();
            this.image.src = params.img;
            this.image.addEventListener("load", (function(obj){
                return function() {
                    obj.createPuzzle(params);
                }})(this));
        } else {
            this.image = params.img;
            this.createPuzzle(params);
        }

    } // Puzzle

    Puzzle.MARGIN1 = 5;
    //--------------------------------------------------------------

    /*
    The given parameter if an object with the following properties :
     -  img, which may be:
      string type : an image url
      object type : an image object (with a ready loaded image)
     -  width : width available for the picture
     -  height : width available for the picture. The script will use the
    width x height space as smartly as possible
     -  npieces : number of pieces. May be any (sensible) integer, the script
    will choose a number of columns and rows to have pieces as square as possible,
    and an actual total number of pieces as close as possible to this integer.
     -  idiv : div which will contail the game

    */

    Puzzle.prototype.createPuzzle = function(params){

//  let kx, ky, x, y, dx, dy, p1, p2, p3, brd, s1, s2, s3, s4, s5, s6, s7, s8, s9, concav, width, height, nx, ny;

// we change width or height in order to keep the picture size ratio
        let wi = this.image.width;  // from original picture
        let he = this.image.height;

        this.reqHeight = params.height; // requested height
        this.reqWidth = params.width;
        this.height = this.reqHeight - 2 * Puzzle.MARGIN1; // place left on screen including margin
        this.width = this.reqWidth - 2 * Puzzle.MARGIN1; //

        if (wi / he > this.width / this.height) { // actual picture "more horizontal" than game board
            this.height = this.width * he / wi;
        } else {
            this.width = this.height * wi / he;
        }
// end change width or height

// div Game - by name (id) or directly an object
        if (typeof(params.idiv) == 'string') {
            this.divGame = document.getElementById(params.idiv);
        } else {
            this.divGame = params.idiv;
        }
        this.divGame.style.overflow = 'visible';
        this.divGame.style.position = 'relative';

// divBoard
        if (!this.divBoard) {
            this.divBoard = document.createElement('div');
            this.divGame.appendChild(this.divBoard);
        }
        this.divBoard.style.overflow = 'hidden';
        this.divBoard.style.position = 'absolute';
        this.divBoard.style.left = 0;
        this.divBoard.style.top = 0;

        this.listeners = []; // table of eventListeners to remove

        /* provisional dimensions of the game, waiting for actual dimensions which depend
        on number of pieces
        */

        this.divGame.style.width = this.divBoard.style.width = this.width + 2 * Puzzle.MARGIN1 + "px";
        this.divGame.style.height = this.divBoard.style.height = this.height + 2 * Puzzle.MARGIN1 + "px";

// canv for the moving PolyPiece and the full image
        if (!this.canvMobile) {
            this.canvMobile = document.createElement('canvas');
            this.divBoard.appendChild(this.canvMobile);
        }
        this.canvMobile.style.visibility = 'visible';
        this.canvMobile.width = parseFloat(this.divBoard.style.width);
        this.canvMobile.height = parseFloat(this.divBoard.style.height);
        this.canvMobile.style.position = "absolute";
        this.canvMobile.style.top = "0px";
        this.canvMobile.style.left = "0px";

        this.canvMobile.style.zIndex = 50000;

        this.dCoupling = 10; // distance for pieces to couple together, in pixels (on each x and y axis)

        this.canvMobile.getContext("2d").drawImage(this.image,
            0, 0, wi, he,
            Puzzle.MARGIN1, Puzzle.MARGIN1, this.width, this.height);


        if (!this.menu) {
            this.menu = new Menu({
                parentDiv: this.divGame,
                idDivMenu: "divmenu",
                title: "菜单",
                lineOffset: 30,
                lineStep: 30,
                lines: [
                    {text: "更换图片", func: this.loadImage()},
                    {text: "12 片", func: this.returnFunct(12)},
                    {text: "25 片", func: this.returnFunct(25)},
                    {text: "50 片", func: this.returnFunct(50)},
                    {text: "100 片", func: this.returnFunct(100)},
                    {text: "200 片", func: this.returnFunct(200)}
                ]
            });
        }
        if (autoStart) {
            this.npieces = 25;
            this.next();
        }
    } // createPuzzle
    // -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -   -
    // function for menu actions

    Puzzle.prototype.returnFunct = function(nbpieces) {

        let puz = this;
        return function() {
            puz.menu.collapse();
            puz.npieces = nbpieces;
            puz.next();
        }
    } // returnFunct

    // -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -   -

    Puzzle.prototype.loadImage = function () {

        let puz = this;
        return function() {
            puz.menu.collapse();
            uploadFile(() => {},
                {accept: 'image/*',
                    readMethod: 'readAsDataURL',
                    image: puz.image});
        }
    }

    // -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -   -

    Puzzle.prototype.next = function() {

        let nx, ny, np, dx, dy, kx, ky, x, y, p1, p2, p3, brd, s1, s2, s3, s4, s5, s6, s7, s8, s9, concav;
        /* parameters for the shape of pieces edges
        */

        let coeffDecentr = 0.12;

        this.canvMobile.style.visibility = 'hidden'; // hide the full picture

// evaluation of number of pieces

        this.computenxAndny();
        nx = this.nx;  ny = this.ny;

// re - evaluation of the dimensions of the picture, leaving a space for pieces on one side

        if (this.image.width / this.image.height <
            (this.reqWidth - 2 * Puzzle.MARGIN1) / (this.reqHeight - 2 * Puzzle.MARGIN1)) {
            /* actual picture "more vertical" than available place
              leave place on the right side */
            this.width = (this.reqWidth - 2 * Puzzle.MARGIN1) / (nx + 2) * nx;
            this.height = this.width / this.image.width * this.image.height;
            if (this.height > this.reqHeight - 2 * Puzzle.MARGIN1) {
                this.height = this.reqHeight - 2 * Puzzle.MARGIN1;
                this.width = this.height * this.image.width / this.image.height;
            }
            this.freeSpace = 0; // place left on the right
        } else {
            /* actual picture "more horizontal" than available place
                leave place on the bottom side */
            this.height = (this.reqHeight - 2 * Puzzle.MARGIN1) / (ny + 2) * ny;
            this.width = this.height / this.image.height * this.image.width;
            if (this.width > this.reqWidth - 2 * Puzzle.MARGIN1) {
                this.width = this.reqWidth - 2 * Puzzle.MARGIN1;
                this.height = this.width * this.image.height / this.image.width;
            }
            this.freeSpace = 1; // place left under
        }

        let height = this.height, width = this.width;
        this.dx = dx = this.width / nx; // horizontal side of tiling
        this.dy = dy = this.height / ny; // vertical side of tiling

        /* adjust coupling distance to size of tiles */
        this.dCoupling = Math.max(10, Math.min(dx, dy) / 10);

// "clean" the board
        while (this.divBoard.firstChild) this.divBoard.removeChild(this.divBoard.firstChild);
// but keep the canvMobile
        this.divBoard.appendChild(this.canvMobile);

        this.canvMobile.width = this.reqWidth;
        this.divGame.style.width
            = this.divBoard.style.width
            = this.canvMobile.width + "px";

        this.canvMobile.height = this.reqHeight;
        this.divGame.style.height
            = this.divBoard.style.height
            = this.canvMobile.height + "px";

// compute the shapes of the pieces

        /* first, place the corners of the pieces
          at some distance of their theorical position, except for edges
        */

        let corners = [];
        for (ky = 0; ky <= ny; ++ky) {
            corners[ky] = [];
            for (kx = 0; kx <= nx; ++kx) {
                corners[ky][kx] = new Point((kx + alea(-coeffDecentr, coeffDecentr)) * dx, (ky + alea(-coeffDecentr, coeffDecentr)) * dy);
                if (kx == 0) corners[ky][kx].x = 0;
                if (kx == nx) corners[ky][kx].x = this.width;
                if (ky == 0) corners[ky][kx].y = 0;
                if (ky == ny) corners[ky][kx].y = this.height;
            } // for kx
        } // for ky

// Array of raw pieces (straight sides)
        this.pieces = [];
        for (ky = 0; ky < ny; ++ky) {
            this.pieces[ky] = [];
            for (kx = 0; kx < nx; ++kx) {
                this.pieces[ky][kx] = np = new Piece(kx, ky);
// top side
                if (ky == 0) {
                    np.ts.points = [corners[ky][kx],corners[ky][kx + 1]];
                    np.ts.type = "d";
                } else {
                    np.ts = this.pieces[ky - 1][kx].bs;
                }
// right side
                np.rs.points = [corners[ky][kx + 1],corners[ky + 1][kx + 1]];
                np.rs.type = "d";
                if (kx < nx - 1) {
                    if (intAlea(2)) // randomly twisted one one side of the side
                        np.rs.twist(corners[ky][kx],corners[ky + 1][kx], 0.5, 1);
                    else
                        np.rs.twist(corners[ky][kx + 2],corners[ky + 1][kx + 2], 0.5, 1);
                }
// left side
                if (kx == 0) {
                    np.ls.points = [corners[ky][kx],corners[ky + 1][kx]];
                    np.ls.type = "d";
                } else {
                    np.ls = this.pieces[ky][kx - 1].rs
                }
// bottom side
                np.bs.points =[corners[ky + 1][kx],corners[ky + 1][kx + 1]];
                np.bs.type = "d";
                if (ky < ny - 1) {
                    if (intAlea(2)) // randomly twisted one one side of the side
                        np.bs.twist(corners[ky][kx],corners[ky][kx + 1], 1, 0.5);
                    else
                        np.bs.twist(corners[ky + 2][kx],corners[ky + 2][kx + 1], 1, 0.5);
                }
            } // for kx
        } // for ky
        this.associateImage();

    } // function next

    // -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -   -
    // called when picture is loaded

    Puzzle.prototype.associateImage = function() {
        let kx, ky, kn, kp;
        let div, scale, he, wi, offsx, offsy, pc;

        // scale picture
        wi = this.image.width;
        he = this.image.height;

        if (wi / he > this.width / this.height) { // actual picture "more horizontal" than board
            scale = this.height / he;
            offsy = 0;
            offsx = (wi - this.width / scale) / 2; // offset in source picture
        } else { // actual picture "more (or equally)horizontal" than board
            scale = this.width / wi;
            offsx = 0;
            offsy = (he - this.height / scale) / 2; // offset in source picture
        }

        this.mech =  { scale: scale, offsx: offsx, offsy: offsy }; // informations for scaling

// creation of pieces
// table of PolyPieces
        this.polyPieces = [];

        for (ky = 0; ky < this.ny; ky++) {
            for (kx = 0; kx < this.nx; kx++) {
                this.pieces[ky][kx].createDivPiece(this, scale, offsx, offsy);
                this.polyPieces.push(new PolyPiece(this.pieces[ky][kx], this));
            } // for kx
        } // for ky

// random zindex for initial pieces
        arrayShuffle(this.polyPieces);
        this.evaluateZIndex();

        for (kp = 0; kp < this.polyPieces.length; kp++) {
            for (kn = 0; kn < this.polyPieces[kp].pieces.length; kn++) {
                pc = this.polyPieces[kp].pieces[kn];

                this.divBoard.appendChild(pc.theDiv);
                switch(this.freeSpace){
                    case 0 : pc.pTarget = new Point(this.reqWidth - (2.25 + Math.random() / 4) * this.dx, Math.random() * (this.height -  this.dy) - this.dy);break;
                    case 1 : pc.pTarget = new Point(Math.random() * (this.width -  this.dx) - this.dx, this.reqHeight - (2.25 + Math.random() / 4) * this.dy);
                } // switch
            } // for kn
        } // for kp
        window.setTimeout((function(obj) {return function() {obj.launchAnimation()}})(this), 1000);

    } // Puzzle.prototype.associateImage

    // -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -   -

    Puzzle.prototype.addRemovableEventListener = function(event, funct) {

        this.divBoard.addEventListener(event, funct);
        this.listeners.push({event: event, funct: funct});
    } // Puzzle.prototype.addRemovableEventListener
    // -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -   -
    Puzzle.prototype.removeAllListeners = function() {
        let a;
        while (this.listeners.length > 0 ) {
            a = this.listeners.pop();
            this.divBoard.removeEventListener(a.event, a.funct);
        } // while
    } // Puzzle.prototype.removeAllListeners()
    // -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -   -

    Puzzle.prototype.launchAnimation = function() {

        this.anim = {cpt: autoStart ? 200 : 100 };
        this.anim.tmr = window.setInterval((function(puzz){return function(){puzz.animate()}})(this), 20);

    } // launchAnimation
    // -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -   -

    Puzzle.prototype.animate = function() {
        let kp, kn, pc, act, cib;

        if (this.anim.cpt == 0){
            window.clearInterval(this.anim.tmr);
            delete this.anim;

            this.evaluateZIndex();
            this.beginGame();

            return;
        }
        this.anim.cpt--;
        for (kp = 0; kp < this.polyPieces.length; kp++) {
            for (kn = 0; kn < this.polyPieces[kp].pieces.length; kn++) {
                pc = this.polyPieces[kp].pieces[kn];
                act = pc.where();
                cib = pc.pTarget;
                pc.moveTo(new Point((this.anim.cpt * act.x + cib.x) / (this.anim.cpt + 1), (this.anim.cpt * act.y + cib.y) / (this.anim.cpt + 1)));
                if (this.anim.cpt == 0) { delete pc.pTarget ; }
            } // for kn
        } // for kp
    } // Puzzle.prototype.animate

    // -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -   -
    // almost the same as 'animate, mais only to center the picture when game is over

    Puzzle.prototype.animateEnd = function() {
        let xcou, ycou;

        if (this.anim.cpt == 0){
            window.clearInterval(this.anim.tmr);
            delete this.anim;
            return;
        }
        this.anim.cpt--;
        xcou = parseFloat(this.canvMobile.style.left);
        ycou = parseFloat(this.canvMobile.style.top);

        this.canvMobile.style.left = (this.anim.cpt * xcou + this.anim.xfin) / (this.anim.cpt + 1) + "px";
        this.canvMobile.style.top = (this.anim.cpt * ycou + this.anim.yfin) / (this.anim.cpt + 1) + "px";

    } // Puzzle.prototype.animateEnd


    // -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -   -
    // merges polyPieces[n2] and polyPieces[n1] into a new piece
    // removes those pieces and inserts nes one
    // re evaluates z-orders accordingly
    // return index of new polyPiece

    Puzzle.prototype.merge = function(n1, n2) {

        let nppiece, nbpieces, k;
        this.polyPieces[n1].merge(this.polyPieces[n2]); // merges pieces
        nppiece = this.polyPieces[n1]; // save new piece
        if (n1 > n2) {
            this.polyPieces.splice(n1, 1);
            this.polyPieces.splice(n2, 1);
        } else {
            this.polyPieces.splice(n2, 1);
            this.polyPieces.splice(n1, 1);
        }

// will insert nes PolyPiece immediately before the first with less pieces
        nbpieces = nppiece.pieces.length;
        for (k = 0; k < this.polyPieces.length && this.polyPieces[k].pieces.length >= nbpieces; k++) {;}
        // insert new
        this.polyPieces.splice(k, 0, nppiece);

        return k;
    } // puzzle.prototype.merge

    // -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -   -

    Puzzle.prototype.evaluateZIndex = function() {

        let kp, kn, z;
        z = 1;
        for (kp = 0; kp < this.polyPieces.length; kp++) {
            for (kn = 0; kn < this.polyPieces[kp].pieces.length; kn++) {
                this.polyPieces[kp].pieces[kn].theDiv.style.zIndex = z++;
            } // for kn
        } // for kp

    } // Puzzle.prototype.evaluateZIndex

    // -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -   -
    // beginning of game
    Puzzle.prototype.beginGame = function() {

// record offset between mouse coordinates et board origin

        let styl = getComputedStyle(this.divGame);
        this.mouseOffsX = this.divGame.offsetLeft + parseFloat(styl.borderLeftWidth);
        this.mouseOffsY = this.divGame.offsetTop + parseFloat(styl.borderTopWidth);
        this.pieceMove = false; // no selected piece
// set event listeners
        this.addRemovableEventListener("mousedown", (function(puzzle){
            return function(event) {
                event.preventDefault();
                let [x,y] = [event.clientX,event.clientY];
                let newEvent = {x: x, y: y, buttons: event.buttons, origin: "mouse"};
                puzzle.mouseDownGame(newEvent);}})(this));
        this.addRemovableEventListener("mouseup", (function(puzzle){
            return function(event) {
                event.preventDefault();
                let [x,y] = [event.clientX,event.clientY];
                let newEvent = {x: x, y: y, buttons: event.buttons, origin: "mouse"};
                puzzle.mouseUpGame(newEvent);}})(this));
        this.addRemovableEventListener("mousemove", (function(puzzle){
            return function(event) {
                event.preventDefault();
                let [x,y] = [event.clientX,event.clientY];
                let newEvent = {x: x, y: y, buttons: event.buttons, origin: "mouse"};
                puzzle.mouseMoveGame(newEvent);}})(this));

        this.addRemovableEventListener("touchstart", (function(puzzle){
            return function(event) {
                event.preventDefault();
                if (event.touches.length != 1) return;
                let [x,y] = [event.touches[0].clientX,event.touches[0].clientY];
                let newEvent = {x: x, y: y, buttons: null, origin: "touch"};
                puzzle.mouseDownGame(newEvent);}})(this));
        this.addRemovableEventListener("touchend", (function(puzzle){
            return function(event) {
                event.preventDefault();
                let newEvent = {origin: "touch"};
                puzzle.mouseUpGame(newEvent);}})(this));
        this.addRemovableEventListener("touchcancel", (function(puzzle){
            return function(event) {
                event.preventDefault();
                let newEvent = {origin: "touch"};
                puzzle.mouseUpGame(newEvent);}})(this));
        this.addRemovableEventListener("touchmove", (function(puzzle){
            return function(event) {
                event.preventDefault();
                if (event.touches.length != 1) return;
                let [x,y] = [event.touches[0].clientX,event.touches[0].clientY];
                let newEvent = {x: x, y: y, buttons: null, origin: "touch"};
                puzzle.mouseMoveGame(newEvent);}})(this));
    } // Puzzle.prototype.beginGame

    // -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -   -

    // mouseDown during game
    Puzzle.prototype.mouseDownGame = function(event) {
// ignore if not left button only
        if (event.origin == "mouse" && (event.buttons != 1)) return;
        this.pieceMove = this.lookForPiece(event) ;
        if (this.pieceMove === false) return;
        this.emphasize(this.pieceMove.pp);
// we will add to the 'this.pieceMove' object the offset between mousePosition and
//   canvMobile position for proper movement of canvMobile when mouse moves

        this.pieceMove.offsx =  event.x - this.mouseOffsX - parseFloat(this.canvMobile.style.left);
        this.pieceMove.offsy =  event.y - this.mouseOffsY - parseFloat(this.canvMobile.style.top);
        this.divGame.style.cursor = 'move';

    } // Puzzle.prototype.mouseDownGame
    // -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -   -

    // mouseUp during game
    Puzzle.prototype.mouseUpGame = function(event) {

        let k, polyP, pc;

        this.divGame.style.cursor = 'default';

        if (this.pieceMove === false) return;

// hide the canvasMobile which was used for the moving piece
        let canvx = parseFloat(this.canvMobile.style.left);
        let canvy = parseFloat(this.canvMobile.style.top);
        this.canvMobile.getContext("2d").clearRect(0, 0, this.canvMobile.width, this.canvMobile.height);

// display again original pieces
        polyP = this.polyPieces[this.pieceMove.pp];
        for (k = 0; k < polyP.pieces.length; k++) {
            pc = polyP.pieces[k]
            pc.moveTo (new Point( this.dx * (pc.kx - 1) + canvx, this.dy * (pc.ky - 1) + canvy));
            pc.theDiv.style.visibility = 'visible';
        } // for k

// check if moved piece is close enough of another to merge them
//  check again with the result of the merge operation

        let idp = this.pieceMove.pp;
        let yesMerge = false, yesyesMerge = false;
        do {
            yesMerge = false;
            polyP = this.polyPieces[idp];
            for (k = 0; k < this.polyPieces.length; k++) {
                if (k ===  idp) continue; // don't check neighborhood with itself !
                if (polyP.ifNear(this.polyPieces[k])) { // yes !
                    idp = this.merge(k, idp); // merge and keep track of index of merged piece
                    yesMerge = true; yesyesMerge = true; // 2 pieces merging
                    break; // out of  'for' loop
                } // if we found a piece
            } // for
        } while (yesMerge) ; // do it again if pieces werge merged

// if no merging, move (if this.polypieces) the selected PolyPiece before
// those with the same number of pieces

        if (! yesyesMerge) {
            let tmp = this.polyPieces[idp]; // memorize polyPiece
            this.polyPieces.splice(idp, 1); // remove from list
            for (k = idp; (k < this.polyPieces.length) && (this.polyPieces[k].pieces.length >= tmp.pieces.length); k++) ;
            this.polyPieces.splice(k, 0, tmp); // re-insert at the right place
        } // if no merging

        this.evaluateZIndex();
        this.pieceMove = false;

// won ?
        if (this.polyPieces.length > 1) return; // no, continue

// YES ! tell the player
        this.removeAllListeners();
// normal image is re-drawn
        let ctx = this.canvMobile.getContext("2d");
        ctx.drawImage(this.image,
            this.mech.offsx, this.mech.offsy,
            this.width / this.mech.scale, this.height / this.mech.scale,
            0, 0,
            this.width, this.height);
        this.anim = {cpt: 100, xorg: 0, yorg: 0, xfin: (this.reqWidth - this.dx * this.nx) / 2,
            yfin: (this.reqHeight - this.dy * this.ny) / 2};

        this.anim.xorg = parseFloat(this.polyPieces[0].pieces[0].theDiv.style.left) + this.dx;
        this.anim.yorg = parseFloat(this.polyPieces[0].pieces[0].theDiv.style.top) + this.dy
        this.canvMobile.style.left = this.anim.xorg + "px";
        this.canvMobile.style.top = this.anim.yorg + "px";

// hide pieces
        for (k = 0; k < this.polyPieces[0].pieces.length; k++) {
            this.polyPieces[0].pieces[k].theDiv.style.visibility = "hidden";
        } // for k

// launch final animation

        let dist = Math.sqrt(
            (this.anim.xorg - this.anim.xfin) * (this.anim.xorg - this.anim.xfin) +
            (this.anim.yorg - this.anim.yfin) * (this.anim.yorg - this.anim.yfin));
// we want a speed of about 100 pix / s
// the time increment beeing of 20 ms, this leads to 100 * 0.02 = 2 pix / pass
        this.anim.cpt = dist / 2;
// limit the duration to the range 0.25..2s, i.e.12..100 steps
        if (this.anim.cpt < 12) this.anim.cpt = 12;
        if (this.anim.cpt > 100) this.anim.cpt = 100;
        this.anim.cpt = Math.floor(this.anim.cpt);
        this.anim.tmr = window.setInterval((function(puzz){return function(){puzz.animateEnd()}})(this), 20);

    } // Puzzle.prototype.mouseUpGame
    // -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -   -

    // mouseMove during game
    Puzzle.prototype.mouseMoveGame = function(event) {

        if (this.pieceMove === false) return;

// for the case where button was released out of 'good' area
        if (event.origin == "mouse") {
            if ((event.buttons & 1) == 0) { this.mouseUpGame(event); return; }
        }

        let x =  event.x - this.mouseOffsX;
        let y =  event.y - this.mouseOffsY;
        if (x < 2) x = 2;
        if (x > Math.floor(parseFloat(this.divBoard.style.width)) - 2) x  = Math.floor(parseFloat(this.divBoard.style.width)) - 2;
        if (y < 2) y = 2;
        if (y > Math.floor(parseFloat(this.divBoard.style.height)) - 2) y  = Math.floor(parseFloat(this.divBoard.style.height)) - 2;

        this.canvMobile.style.left = (x - this.pieceMove.offsx) + "px";
        this.canvMobile.style.top = (y - this.pieceMove.offsy) + "px";

    } // Puzzle.prototype.mouseMoveGame

    // -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -   -
    // searches the pieces whick was clicked on
    // event is the click event
    // returned value : (index of PolyPiece + piece) or false (if not on a piece)

    Puzzle.prototype.lookForPiece = function(event) {

        let kp, kn, z;
        let x =  event.x - this.mouseOffsX;
        let y =  event.y - this.mouseOffsY;
        for (kp = this.polyPieces.length - 1; kp >= 0; kp--) {
            for (kn = this.polyPieces[kp].pieces.length - 1; kn >= 0; kn--) {
                if (this.polyPieces[kp].pieces[kn].insidePiece(x, y)) return {pp: kp, pc: kn};
            } // for kn
        } // for kp

        return false; // found nothing
    } // Puzzle.prototype.lookForPiece

    // -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -   -
    // emphasizes a polyPiece
    // its idividualpieces are masked (style.visibility = "hidden")
    // but they are collectively drawn on canvMobile
    // parameter : polyPiece index

    Puzzle.prototype.emphasize = function(npp) {

        let kbcl, kc, k;
        let ppc = this.polyPieces[npp]; // current PolyPiece
        let ctx = this.canvMobile.getContext("2d");
        let loops = lookForLoops(ppc.pieces);
        let edge;

        ctx.save();
        ctx.clearRect(0, 0, this.canvMobile.width, this.canvMobile.height);
        ctx.beginPath();
        for (kbcl = 0;kbcl < loops.length; kbcl++) {
            for (kc = 0; kc < loops[kbcl].length; kc++) {
                edge = loops[kbcl][kc];

                switch (edge.edge) {
                    case 0 : ppc.pieces[edge.kp].ts.drawPath(ctx, 0, 0, false, (kc!= 0)); break;
                    case 1 : ppc.pieces[edge.kp].rs.drawPath(ctx, 0, 0, false, (kc!= 0)); break;
                    case 2 : ppc.pieces[edge.kp].bs.drawPath(ctx, 0, 0, true, (kc!= 0)); break;
                    case 3 : ppc.pieces[edge.kp].ls.drawPath(ctx, 0, 0, true, (kc!= 0)); break;
                }
            } // for kc
        } // for kbcl;

// make shadow
        ctx.fillStyle = 'none';
        ctx.shadowColor = 'rgba(0, 0, 0, 0.5)';
        ctx.shadowBlur = 4;
        ctx.shadowOffsetX = 4;
        ctx.shadowOffsetY = 4;
        ctx.fill();

// add image clipped by path
        ctx.clip('evenodd');
// reset shadow else FF does not clip image
        ctx.shadowColor = 'rgba(0, 0, 0, 0)';
        ctx.shadowBlur = 0;
        ctx.shadowOffsetX = 0;
        ctx.shadowOffsetY = 0;

        ctx.drawImage(this.image,
            this.mech.offsx, this.mech.offsy,
            this.width / this.mech.scale, this.height / this.mech.scale,
            0, 0,
            this.width, this.height);

// hide original PolyPiece
        for (k = 0; k < ppc.pieces.length; k++) {
            ppc.pieces[k].theDiv.style.visibility = "hidden";
        } // for k

        ctx.restore();

// set picture position to hide previous one
        this.canvMobile.style.left = (ppc.pieces[0].where().x - (ppc.pieces[0].kx - 1) * this.dx) + "px";
        this.canvMobile.style.top = (ppc.pieces[0].where().y - (ppc.pieces[0].ky - 1) * this.dy) + "px";
        this.canvMobile.style.visibility = 'visible';

    } // emphasize

    // -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -   -

    // checks if p1 and p2 pieces are close to each other
    // dx is -1, 0 or 1 to check left, (top or bottom) or right side of p1
    // dy is -1, 0 or 1 to check top, (left or right) or bottom of p2

    Puzzle.prototype.near  = function (p1, p2, dx, dy) {
        let ou1 = p1.where();
        let ou2 = p2.where();

        if (Math.abs (ou1.x - ou2.x + dx * this.dx) > this.dCoupling) return false;
        if (Math.abs (ou1.y - ou2.y + dy * this.dy) > this.dCoupling) return false;
        return true;
    } // near

    // fin class puzzle

    // -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -   -
    /* computes the number of lines and columns of the puzzle,
      finding the best compromise between the requested number of pieces
      and a square shap for pieces
    */

    Puzzle.prototype.computenxAndny = function() {

        let kx, ky, width = this.image.width, height = this.image.height, npieces = this.npieces;
        let err, err2, errmin = 1e9;
        let ncv, nch;

        let nHPieces = Math.round(Math.sqrt(npieces * width / height));
        let nVPieces = Math.round(npieces / nHPieces);


        /* based on the above estimation, we will try up to + / - 2 values
           and evaluate (arbitrary) quality criterion to keep best result
        */

        for (ky = 0;ky < 5;ky++) {
            ncv = nVPieces + ky - 2;
            for (kx = 0;kx < 5;kx++) {
                nch = nHPieces + kx - 2;
                err = nch * height / ncv / width;
                err = (err + 1 / err) - 2; // error on pieces dimensions ratio)
                err += Math.abs(1 - nch * ncv / npieces); // adds error on number of pieces

                if (err < errmin) { // keep smallest error
                    errmin = err;
                    this.nx = nch;
                    this.ny = ncv;
                }
            } // for kx
        } // for ky

    } // computenxAndny

    //---------------------------------------------------------------------------- -
    //---------------------------------------------------------------------------- -

    /* algorithm to determine the boundary of a PolyPiece
      input : a table of cells, hopefully defining a 'good' PolyPiece, i.e. all connected together
      every cell is given as an object {kx: indice, ky: indice} representing an element of a 2D array.

      returned value : table of Loops, because the boundary may be made of several
    simple loops : there may be a 'hole' in a PolyPiece
    every loop is a list of consecutive edges,
    every edge if an object {kp: index, edge: b} where kp is the index of the cell ine
    the input array, and edge the side (0(top), 1(right), 2(bottom), 3(left))
    every edge contains kx and ky too, normally not used here
    */

    function lookForLoops (tbCases) {

// -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -
// internal : checks if an edge given by kx, ky is common with another cell
// returns true or false

        function edgeIsCommon (kx, ky, edge) {
            let k;
            switch(edge) {
                case 0 : ky--; break; // top edge
                case 1 : kx++; break; // right edge
                case 2 : ky++; break; // bottom edge
                case 3 : kx--; break; // left edge
            } // switch
            for (k = 0; k < tbCases.length;k++) {
                if (kx == tbCases[k].kx && ky == tbCases[k].ky) return true; // we found the neighbor
            }
            return false; // not a common edge
        } // function edgeIsCommon

// -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -
// internal : checks if an edge given by kx, ky is in tbEdges
// return index in tbEdges, or false

        function edgeIsInTbEdges (kx, ky, edge) {
            let k;
            for (k = 0; k < tbEdges.length;k++) {
                if (kx == tbEdges[k].kx && ky == tbEdges[k].ky && edge == tbEdges[k].edge) return k; // found it
            }
            return false; // not found
        } // function edgeIsInTbEdges

// -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -

        let tbLoops = []; // for the result
        let tbEdges = []; // set of edges which are not shared by 2 pieces of input
        let k;
        let kEdge; // to count 4 edges
        let lp; // for loop during its creation
        let currEdge; // current edge
        let tries; // tries counter
        let edgeNumber; // number of edge found during research
        let potNext;

// table of tries

        let tbTries = [
            // if we are on edge 0 (top)
            [
                {dkx: 0, dky: 0, edge: 1}, // try # 0
                {dkx: 1, dky: 0, edge: 0}, // try # 1
                {dkx: 1, dky: -1, edge: 3} // try # 2
            ],
            // if we are on edge 1 (right)
            [
                {dkx: 0, dky: 0, edge: 2},
                {dkx: 0, dky: 1, edge: 1},
                {dkx: 1, dky: 1, edge: 0}
            ],
            // if we are on edge 2 (bottom)
            [
                {dkx: 0, dky: 0, edge: 3},
                {dkx: - 1, dky: 0, edge: 2},
                {dkx: - 1, dky: 1, edge: 1}
            ],
            // if we are on edge 3 (left)
            [
                {dkx: 0, dky: 0, edge: 0},
                {dkx: 0, dky: - 1, edge: 3},
                {dkx: - 1, dky: - 1, edge: 2}
            ],
        ];


// create list of not shared edges (=> belong to boundary)
        for (k = 0;k < tbCases.length;k++) {
            for (kEdge = 0; kEdge < 4; kEdge++) {
                if (!edgeIsCommon(tbCases[k].kx, tbCases[k].ky, kEdge))
                    tbEdges.push({kx: tbCases[k].kx, ky: tbCases[k].ky, edge: kEdge, kp: k})
            } // for kEdge
        } // for k

        while (tbEdges.length > 0) {
            lp = []; // new loop
            currEdge = tbEdges[0];   // we begin with first available edge
            lp.push(currEdge);       // add it to loop
            tbEdges.splice(0, 1);    // remove from list of available sides
            do {
                for (tries = 0; tries < 3;tries++) {
                    potNext = tbTries[currEdge.edge][tries];
                    edgeNumber = edgeIsInTbEdges(currEdge.kx + potNext.dkx, currEdge.ky + potNext.dky, potNext.edge);
                    if (edgeNumber === false) continue; // can't here
                    // new element in loop
                    currEdge = tbEdges[edgeNumber];     // new current edge
                    lp.push(currEdge);              // add it to loop
                    tbEdges.splice(edgeNumber, 1);  // remove from list of available sides
                    break; // stop tries !
                } // for tries
                if (edgeNumber === false) break; // loop is closed
            } while (1); // do-while exited by break
            tbLoops.push(lp); // add this loop to loops list
        } // while tbEdges...
        return tbLoops;
    } // function lookForLoops

    //---------------------------------------------------------------------------- -

    window.addEventListener("load", function(){

        let img = 'https://gimg2.baidu.com/image_search/src=http%3A%2F%2Fi0.hdslb.com%2Fbfs%2Farchive%2F0efb3d506718647498726d5344db9ce94ec86985.png&refer=http%3A%2F%2Fi0.hdslb.com&app=2002&size=f9999,10000&q=a80&n=0&g=0n&fmt=auto?sec=1664507977&t=76e995c47f70dd34af369212a8375019';

        autoStart = isMiniature(); // used for nice miniature in CodePen

        let x = new Puzzle ( {img: img,
            width: window.innerWidth,
            height: window.innerHeight,
            idiv: "forPuzzle" });

    });

</script>
</body>
</html>